Non Genuine pattern part. This is a flat backed idler pulley used on various machines manufactured by Castelgarden. Outer diameter 52mm, internal diameter 15mm. Dust cap to prevent water build up in top of pulley and damage to bearing is available seperately under part number 125109521-1. Castelgarden is an Italian manufacturer that produces many lawn tractors and mowers that are sold in the UK under various brands including Honda, Lawnking, John Deere, Efco, Mountfield. Also available as a genuine part by searching part number 325601570-0